The Butterfly Effect
by RayvnAshes2
Summary: Kaori tells a different lie, and this time Watari is in on her 'plot' from the beginning. How will this one small difference influence the story? Three-shot, rated T to be safe, Kaori x Kousei, Enjoy!
1. Another Lie

**Disclaimer: I don't own anything in this story, from the plot to the characters to the music.**

 **Concept: Kaori tells a different lie, and this time Watari is in on it. How would that change the story?**

 **Enjoy! :)**

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Kaori took a deep breath, bowing her head so that her wavy blonde hair covered her face.

After weeks of trying to figure out a way to befriend a certain trio of her classmates, she thought that she had finally thought of something that might work. Something that would help the long-time friends accept her into their group.

But there was something—no, some _one,_ who was vital to her idea, and considering the part she hoped he would play, she refused to go through with it unless she had his permission first.

But first she had to explain everything to him, and hope to kami that he agreed. If he didn't, Kaori didn't know what she would do. The thing she most wanted to do before she died depended on this, and if she didn't grab onto it with both hands…well.

Her time was limited.

And so here she was, waiting until football (AN: soccer to Americans) practice let out, as the boy she was waiting for was the team captain.

After another fifteen minutes of waiting, she saw him.

Ryōta Watari.

With light caramel brown hair and eyes and a lean body, he was considered good-looking. His easygoing and flirtatious attitude only endeared him further to the girls at their school, though some were put off by that same flirtatiousness.

Kaori herself didn't particularly mind it. From what she could tell Watari-san was a good person and a great friend. He might be a little flighty with the girls, but as she didn't have romantic feelings for him (she wanted someone more sincere) that wasn't a problem.

"Miyazono-san, right?" she heard a voice say, and the blonde shook her head, coming back to reality. "Most students in the school clubs left a while ago. Are you waiting for someone?"

Kaori bit her lip. "Y-yes, actually. I was…hoping I could speak with you. Yoroshiku."

(AN: Yoroshiku is a loose translation of 'please take care of me', which can have numerous meanings and is used in various situations, especially when introducing yourself. This is informal.)

Watari blinked in surprise. What could Miyazono Kaori have to talk to him about?

He'd had a fair few girls from school confess to him, but despite his confidence in his talents with the ladies, he got the feeling that this was about something different. Miyazono-san had never really seemed attracted to him anyway, from their limited interactions.

In fact…he seemed to remember her glancing at _Kousei_ a few times, usually with what seemed to be a mix of sadness and hesitance.

"Okay." He said after a moment. "Anywhere you want to go in particular?"

He grinned slyly as he came to the conclusion that she had a crush on his best guy friend, Arima Kousei, and wanted him to introduce her to him. He had noticed a few weeks ago that her looks had changed from black glasses to contact lenses (and wow, the full brunt of those large blue/gray eyes was enthralling, even when she was nervous) and she had let her long hair down from their previous pigtail style. Maybe she had needed a makeover in order to gain the confidence to act on her crush?

The blonde bit her lip thoughtfully. "Um…my parents own a bakery. We could go there?"

"Sure." Watari agreed, hoping to lessen her apparent nervousness a bit. "Do you have dango? I've got a bit of a craving…"

For the first time during their conversation, Kaori quirked a smile, and her eyes brightened, making them even more dazzling to look at.

Watari chided himself mentally. This girl probably had a crush on Kousei, given the stares she'd given the oblivious former pianist, and there was no way he was going to get in the middle of that.

"We do." She agreed with a laugh. "And more than that. You should try the cannoli my parents make."

"That's the…Italian pastry thing, right?" he asked, tilting his head curiously. "My mom's mentioned them before. She studied abroad before I was born."

Kaori beamed at him, and he knew that he had said the right thing when she went into a passionate diatribe about the wonders of the cannoli.

He was eerily reminded of the near worship Kousei had for egg sandwiches.

As he thought about that, he grinned more broadly, now determined to try and set them up even if he was wrong and that wasn't what she wanted to talk to him about.

After all, for a person with a food obsession like that, who better to start a relationship than someone who could understand it, even for a different food?

It would be a simple matter to ignore his physical attraction for her, everything considered. He wouldn't mind getting to know her, of course, but he was already thinking about her with Kousei. Sure, she was beautiful, with her blonde hair and blue/gray eyes, but he preferred brown…

He coughed slightly as he remembered one particular issue with getting Kousei and the Miyazono girl up.

"Are you okay?" the blonde asked.

He grinned sheepishly, though his thoughts were more solemn.

Tsubaki had a huge crush on Kousei that not only Kousei was oblivious to, but Tsubaki herself hadn't yet realized. He wanted her to be happy and not get hurt, but he also knew that Kousei didn't see her as anything more than a sister and friend.

"Ryōta-san?" Miyazono interrupted his thoughts, and Watari turned back to the girl in surprise.

"Ah, sorry, Miyazono-san." He said sheepishly. "I was just…lost in thought."

"If you're sure." She agreed, before biting her lip. "And just Kaori is fine. I'm not really a formal type of person."

He grinned at her cheerfully. "Neither am I. Okay, then. Call me Watari, and you have yourself a deal."

She smiled back slightly, nodding her head in assent, and they continued in silence for a few more blocks until they reached a small bakery.

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 **Please review! :)**


	2. The Plan

**Disclaimer: I don't own Your Lie in April or anything else.**

 **Note: I've decided to just make this a three-shot. The rest can be left to your imagination. :)**

 **Enjoy!**

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Stepping inside, Watari smiled at the warm, cozy feel to the place. That, paired with the smell coming from the baked good behind the counter, made him think that he would end up becoming a regular customer.

"Kaori, sweetie!" a kind-looking woman behind the daughter called out, smiling widely and coming to give her daughter a hug.

"Mom!" Kaori greeted with a similar smile, and Watari noticed that she seemed significantly more comfortable now that she was in familiar surroundings. "I wanted to hang out with one of my classmates. Can we have some dango and cannoli? ~ _Please?_ "

The woman laughed, sending Watari a smile, though he noticed a slight suspicion and confusion in her gaze.

"I promise I'll explain later, mom." Kaori assured her quietly, smiling awkwardly. "Just…don't let dad scare him, please?"

The woman gave her daughter a long, appraising look before nodding in agreement. Within a minute they had their snack in front of them and they were sitting at one of the tables in the corner.

"So…you want me to introduce you to Kousei." Watari said, waiting until she had taken a bite out of her chocolate-covered cannoli.

As expected, she choked slightly, eyes widening. Swallowing carefully, she glanced at him, startled, and slightly…fearful?

No, that wouldn't do.

"I can do that." He continued, not wanting her to get more anxious. "But I am wondering why you didn't just introduce yourself."

She was quite for a long moment, glancing down to where her hands were folded on her lap. After a moment she looked back up at him.

"You all seem so close-knit." She said quietly. "You've known each other since forever. I don't know how to…well, make friends. I…"

She closed her eyes, tears starting to pour down her cheeks, and Watari's eyes widened.

"Woah, it's okay!" he yelped, slightly panicked as he tried to figure out how to comfort her. "I wasn't accusing you of anything, I was just—"

"No, it's okay." She said, shaking her head as her tears stopped. "It's just a sensitive topic. I've already come to you for help, so I might as well tell you the whole story. It started when I was a kid, maybe eight years old or so."

Watari's eyes widened.

This was more complicated than he had assumed, wasn't it?

"You see…when I was little, I had surgery." She said quietly, not looking up from her lap. "I've always been pretty frail, and it's gotten worse over the years. I've spent most of middle school so far in the hospital. That's why…well, why I haven't really had much chance to form friendships."

Watari cursed quietly, which Kaori either ignored or didn't notice. She still hadn't looked up from her lap.

"About four months ago during one of my stays in the hospital, when I was supposed to be asleep I came out of my room to see my parents crying into each other's arms. No one had ever really told me how bad my illness was—heck, I'm not even sure what my illness _is_ , but from the looks on their faces…I don't have much longer."

Watari dropped the stick of dango, not paying attention to it at all as he stared at his classmate, who was clearly trying to hold herself together.

He couldn't even begin to imagine what she was going through, knowing that…she was dying. Or soon would be.

"What do you need from me?" he asked quietly. "Whatever it is, I'll try my best to help."

Because it truly was a matter of what she _needed_ , not what she wanted.

She took a deep breath. "Well, that's only part of my story. See, when I was eight I took piano classes, and one day we took a field trip to see a showcase."

"Kousei." Watari realized, knowing that his friend had been hailed as a prodigy back when he still played.

Kaori nodded in agreement. "It was amazing, needless to say, and when I got home I immediately asked my parents to switch out my piano classes for violin. See, some violinists play with an accompanying pianist, and my child-logic decided that if I switched, someday I would be able to play alongside him. By the time I realized that wasn't exactly realistic, I'd grown to love playing the violin on its own merit, and I had mostly given up on that dream. But then I realized that Kousei-sama went to the same school as me, and I found out about my time limit…"

Watari rubbed at his eyes, emotions rampant as he tried to understand, to _grasp_ , the depth of feelings he could tell Kaori already had for Kousei. The determination and stubbornness in her eyes only made him more confident that Kousei would end up falling for her.

Good, he decided. Kousei needed some color in his life.

"And my role in this is to introduce you two?" Watari clarified.

"Oh, please don't say it like that!" she groaned, burying her head into her hands. "It's so demeaning! I asked you instead of Tsubaki because you're more approachable, and, well…"

Watari nodded, understanding her unspoken point that approaching Tsubaki to ask her to introduce Kaori to Kousei would be a bad move, considering the brunette's own unrealized feelings for the former pianist.

"I don't mind. And I can do that." He assured her with a sincere smile, praying to any deity listening that all parties involved would come out of this unhurt, though he didn't think it likely considering Kousei didn't return Tsubaki's feelings. And then of course there was Kaori's condition… "Do you have any preference of _how_ you want to be introduced?"

The blonde ducked her head again before glancing up at him sheepishly. "Well, my first thought was to ask Tsubaki to introduce me to both of you and tell her that I had a thing for _you._ "

Watari blinked in surprise.

He wondered if he was gullible enough to believe that, if she had gone with that plan. He hoped not, since he was already sure that she actually had feelings for Kousei, if not quite love because she didn't actually know him as a person, just through the music he had played during the one performance.

"You could do that," he agreed thoughtfully. "But I don't think that would work very well. Kousei is a very loyal person, and if he thought he was 'stealing you' from me in any way, then he would try and keep his distance from you."

 _Especially if he ends up returning your feelings…_

Kaori's shoulders slumped. "Well, I'm glad I didn't go through with it, then."

Watari smirked in agreement. "Beyond that, I could introduce you as a childhood friend."

Kaori shook her head immediately. "Childhood friends share a history, and we don't know each other very well. It would become unraveled too easily."

"A new friend?" Watari tried.

Kaori smiled genuinely. "Tsubaki would be on guard whenever I talk to Kousei. Assuming she ever realizes what everyone else but her and Kousei know, anyway."

Watari smiled again, this time sadly, before straightening as an idea hit him. "Cousins!"

The blonde girl blinked at him. "We've gone to the same school for two years. Why would you only be introducing me now?"

He smirked at her. "Easy: we didn't know. Tsubaki and Kousei know my family had a reunion a few weeks ago, so we could use that. I mention I wanted to keep you to myself for a while before introducing you, and viola!"

Her eyes brightened. "Watari, you're a genius!"

He grinned back at her. "Not often I hear that. Makes for a nice change."

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 **Please review! :)**


	3. Wheels in Motion

**Disclaimer: I don't own Your Lie in April.**

 **Note: this is the last chapter, the rest is left up to your imagination! Though I'll admit that for me, Kaori survives because, since she's not keeping her illness from Watari, he encourages her to take it easy and she has that surgery earlier when she has better chances of survival.**

 **Enjoy!**

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"Hey, Tsubaki!" Watari called, waving his arms at his friend, who was just now being let out of softball practice.

"Watari?" Tsubaki blinked, surprised that he'd bothered waiting for her, since his own practice had let out a bit earlier. "What's up?"

"Do you have a minute?" he asked, intentionally not answering her question.

"Sure, I guess." The brunette said with a shrug. "An actual minute, or can I change first?"

Noticing his friend pulling slightly at the collar of her shirt, Watari waved her off to the locker rooms, content to wait a few minutes.

He grinned when Tsubaki emerged only a few minutes later, appreciating the fact that she didn't take forever getting ready like some of their classmates. Not that she needed to.

"So?" she asked, jumping to sit on the railing Watari was leaning against.

"You know that family reunion my folks took me to a few weeks ago?" he asked, earning a nod. "Well, as it turns out, one of my cousins goes to our school. Neither of us knew we were related until then, though."

"Woah, seriously?!" Tsubaki asked, glancing down at him in surprise. "Neither of you? Wait…please tell me she's not one of the girls who has a crush on you. Finding out you were related probably would have been heartbreaking for her…"

Watari grinned, pleased that his friend was taking Kaori's feelings into account before even meeting the girl. "Nah, she doesn't. Didn't. Whatever."

"Good." Tsubaki sighed, relieved. "So when are we going to meet her?"

"We?" Watari repeated in question, though he knew exactly who else she meant.

"Me and Kousei, of course." She scoffed, rolling her eyes a bit.

Of course.

Instead of asking when _she_ could meet her, her mind automatically included Kousei, as if she couldn't so much as entertain the idea that they were individuals who can do things by themselves as opposed to a pair of friends who might as well be attached at the hip.

Watari dreaded the thought of Tsubaki realizing that she was in love with Kousei, not so much because of his own crush on the girl, but because he was sure that Kousei didn't— _couldn't_ see her in a romantic light and that she would be heartbroken.

Assuming she ever did realize her feelings, anyway.

Ugh. And now he felt guilty that he was helping Kaori with her own feelings for Kousei, even if the blonde was sure that she wouldn't live long enough for it to really become much of an issue.

He had a feeling that that feeling would make itself known quite frequently over the next…well, however long it lasted. Hopefully longer than his 'cousin' thought it would.

"I was thinking sometime next week." Watari answered lightly, not letting on about his inner conflict. "She plays the violin, and she has a competition at Towa Hall on Tuesday. She's a bit nervous, and I figured we could show our support."

Tsubaki smiled at the idea, but had a hesitant look in her eyes. "You know Kousei won't—"

"We'll keep it a surprise." Watari shrugged. "Maybe meet up at the park in front of the building under the guise of just meeting and hanging out with Kaori, and then drag him inside right before the performance."

"Yeah, that should work." Tsubaki nodded firmly, before her mouth opened in slight surprise as she recognized the new name. "Wait, did you say Kaori? Like, Miyazono Kaori?"

"Um, yeah." Watari nodded, desperately hoping that that really was Kaori's last name. It wouldn't look good if he didn't know his supposed cousin's family name. "You know her?"

"She's in a couple of my classes." Tsubaki explained with a grin. "She seems cool, I guess. I haven't had much opportunity to talk to her. I wouldn't have guessed she's a musician, too."

Like Kousei.

She hadn't said it, but Watari heard it anyway.

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 **Please review! Thanks for reading! :)**


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